Electric resistance welding installation



I Aug. 5, 1941. QHAGEDQRN 2,251,877

ELECTRIC RESISTANCE WELDING INSTALLATION Filed May 26, 1939 CONTIIIUOUS CURRiNT ALTERNATING (,uRRn

DISCHARGE 'CMRG [TUBE RRENT pf TH QPERKTIVF.

VOLTAGE CONDENSER VOLTAGE Fly- / VOLTAGE or THE was /9 fgig fi am Patented 'Aug.- '5, 1941 UNITED ELECTRIC RESISTANCE WELDING INSTALLATION Gerhard Haledorn. Berlln-mohterlelde, Ger.- mnny, asslgnor to Bernhard Bel-glans, Berlin- Lankwltz, Germany Application May 26, 1939, Serial No. 275,970

In Ge June 3, 193

The present invention relates to an electric resistance welding installation for medium and high frequencies, the characteristic feature of w'luch is that the medium or high frequency sfiormer is fed by tube generator. mmdn tally the tube generator consists cl at source continuous current connected in semen with lg cell, at grid-controlled. tube connected ellel end an oscillatory circuit consisting condenser and a. welding transformer con .2 ml in ncrs lel with the tube, The tube elebly consists of cgrldwoutsolled mercury .n pom tube. Moreover, the wurce of continuous; curscnt is connected in cmnllel with on ncoumu uervlug as '1 a the network. by n e A stew of eccumulctom intention in infiltrated he" new of example in the ncccmpunylnn dmwhig, in which Flgl l is a diagram of ccnnectlem of an elecmc resistance welding installation for medium nnol high frequencies with a tube generator for con tlnuous current supply;

Fig. 2 ls a diagram showing the current end voltage characteristics of the arrangement shown in Figure 1; and

Fig. 3 is a. second arrangement or an electrlc resistance welding installation for medium and high drequencles with tube generator, in the case cl n three-phase supply through a rectifier.

Referring to the arrangement shown in Figure .1, the installation comprises a source of continu- Y The welding electrodes are illustrated at I and 8 andlandllsretheportstobeweldsdtogether, Abuflerbotterylllsoonnectedlnporsllelwlth' the controlling tube .1- the conneotlon being y of suclrz an arrangement it is pcuel e and a, second resistance 26 to the cathode 22: The two ends of the resistance 28 are connected over as switch 23 to the condenser 5, The prlmax-y of the welding transformer ls connected at one end to the main anode of the controlling 3 to point between the switch 23 and th condom $0 With newer required ifcz normal resistance welding, gee or vapour dlschcrge tubes such as mercury vapour tubes are preiembly used. The controlling tube essentially presents as variable ohmic insistence whlch, w the tube ls on condom, is then 25 ohm, increasing to infinite value when the tube is entlng duheeh such as tntluble traversed by nllowe continuous and alternating co e ergy be exchanged At the en la t 2" me is the sect oil on nltemn The object on? ch e ultel voltage a l i'lcw tuhe the chccslmg culteble ccnstentc tor the l a: curzcent circuit containing; the con deuce? 8* letter dlcchumcs as n nerlodlc oscll laden The continuous and oltemetlng current flow first of all tn the same direction through the tube, then the alternating ctwrent changes its direction, reaching finally the value 0: the contlnuous current at the time in as shown in Fig. 2. At this moment the arc is extinguished. The grid, the potential of which with respect to the cathode ls dependent upon the potential of the condenser 5 and battery 21!, reaches a stopping potential immediately alter the ignition and prevents lmmedlate re-lgnltlon. Alter the arc has been extinguished the condenser starts to be charged again. The continuous current remains practlcally constant owing to the large choking coll}. When the condemer reaches a sumclently high voltage, the grid ll of the tube 3 also attains lgnitlon potential and the operation is repeated from ts. Naturally the voltsge o! the battery II must be smaller then the continuous current voltage of the source I. The oscillations my be started and interrupted by means of the switch :I. By constructing the switch as a time switch it on determln'ethe period or Naturally the grid may be connected up in many other won. The lnstsllatton is mainly intended for comparatively blah frequency since,

5 lnthatcssmthecondenlcrlcanbemadesmall.

At the time the advantage is obtained that the tronc'ormerd new he made small can be ebcox'bed 11, cc-

nn a bettery .ox accumu-'-.

lators i l is connected in parallel with the source of continuous current 1 through a switch i3. The voltage of the source of continuous current is adjusted to be. so high when it runs idle that a definite charg Current flows through the battery. When there is a welding impulse the battery absorbs any desired proportion thereof so long as the voltage drop of the source of continuous current is correspondingly adjusted.

If the installation is fed from a three-phase network 2?, as illustrated in Figure 3, use is preferably made of a source of continuous current in the form of a rectifier and an aux iary load 25. In order to znalce use of small discharge vessels, it is advisable to provide an intermediate transformer since the size of the tube depends preponderantly upon the current intensity. (3n the other hand, however, acertain voltag on the welding transformer 5 must not be exceeded in order to avoid danger.

A buffer battery may also be used with the installation connected up to a three-phase net- 'zvor but ev n enoent h tributes the c 1e great advantage that it uernathig current energy absorbed wily over the threen has been des 4 appare "is an may be ther in and be for other 1:

a primary winding, a condenser connected in ies circuit relation with respect to the primary winding, a grid controlled gaseous discharge tube havlig a cathode and an anode connected across the condenser and the primary winding so that the tube is arranged in parallel circuit relation with respect to the primary windand the condenser to provide an oscillating circuit, a source of direct current, a circuit for connecting said source across the anode and cathode of said tube, a choice coil arranged in said circuit, a d biasing circuit connected to said to said oscillating circuit between primary winding and the condenser.

g circ it 2. ill a resistance welding system, a welding transformer having a. primary winding, con.- denser connected series circuit relation with respect to the primary winding, a grid controlled gas filled discharge tube having a cathode and an anode connected across the condenser and the primary winding so that the tube is arranged in parallel circuit relation with respect to the primary winding and the condenser to provide an oscillating circuit, a source of direct current, a circuit for connecting said source across the anode and cathode of said tube, a choke coil arranged in said circuit, a grid biasing circuit connected to said tube, and a time switch for connecting said grid biasing circuit to said oscillating circuit between the primary winding and the condenser.

3. In an electrical control system, a load transformer having a primary winding, a condenser connected in series circuit relation with the primary winding, a grid controlled mercury vapor discharge tube having a cathode and an anode connected across the condenser and the primary winding so that the tube is arranged in parallel circuit relation with respect to the primary winding and the condenser to provide an oscillating circuit, a source of current, a circuit for connecting said source across the anode and cathode of said tube, a choke coil arranged in said circuit, a grid biasing circuit connected to said tube, a switch connecting said grid biasing circuit to said oscillating circuit between the primary wind ing and the condenser, and energy absorbing means connected across said source.

In an electrical control system, a load trans former having a primary winding, a condenser connected in series circuit relation with the primary winding, a grid controlled gas-filled discharge tube having a cathode and an anode connected across the condenser and winding so that the tube is arranged in parallel circuit relation with respect to the primary circuit, a source connecti: said source a cathode of tube, a cholze coil ar said circuit, grid biasing circuit to said tube, a switch co ecti'ng said ing circuit to oscille circuit bet v current, c. across the former haying rirnary connected in series circuit discharge tube having a cathode and an anode connected across the condenser and the pr circuit relation with espect to the primary winding and tie condense? to provide an oscillat in circuit, a source or alternating currer rectifier for converting the alternating c" into direct current, a circuit for impressing 1e direct current across the anode and said tube, a choice coil arranged in said circuit, a grid biasing circuit connected to said tube, and a switch for conne ing said grid biasing circuit to said oscillating circuit between prldiary winding and the condenser.

6. In an electrical control system, a load former having a primary winding, 0011i connected in series circuit relation with respect to the primary winding, 2. grid controlled gas-e ous discharge tube having a cathode an anode connected across the condenser and the primary winding so that the tube is in parallel circuit relation with respect to the primary winding and the condenser to provide an oscillating circuit, a polyphase source of alternating current, a ClICllb including a rectifier and an auxiliary load connected to said source, a circuit connecting said auxiliary load in parallel circuit relation with respect to said tube, a choke coil arranged in the last mentioned circuit, a grid biasing circuit connected to said tube, and a switch connecting said grid biasing circuit to said oscillating circuit between the primary winding and the condenser.

GERHARD HAGEDORN. 

